Reactive and physical extraction of bio-based diamines from fermentation media

BACKGROUND: The production of polymers constitutes the major mass flow in the chemical industry. The foreseeable future change from fossil to renewable resources leads to the demand for more production routes based on biotechnological conversions. These routes preferably require biocompatible components and possess certain limitations of temperature and pH value for the corresponding downstream processing, which can be met by liquid–liquid extraction. This study investigates the extraction of the monomers hexane-1,6-diamine and butane-1,4-diamine from fermentation media using bis(2-ethylhexyl) hydrogen phosphate and isostearic acid as reactive extractants and kerosene as well as oleyl alcohol as diluents.
RESULTS: As expected, the degree of extraction strongly depends on the pH-value but only weakly on the diluents. A higher diluent polarity leads to a slightly higher degree of extraction at a given pH value. The fraction of reactive extractant can be used to adjust theminimal pH value to reach the desired degree of extraction. No significant influence of fermentationmedium, buffer, presence of an E. coli microorganism, or temperature was detected.
CONCLUSION: Reactive extraction of bio-based diamines with organic acids is feasible. The degree of extraction can be adjusted by the fraction of reactive extractant.